Another reason for expensive wasteful activities, IMO, is
the mundane memetic pressure. Just like fish and peacocks
grow their tails out of all practical proportions, many cultural
traditions tend to exaggerate their symbolic messages, and
put extreme amount of effort into cultural rituals.
All advertising has to do is to guide this energy a little by
suggesting that wasteful practices should be based on
buying stuff (as opposed to physical activities, sacrifices,
and other non-consuming activities that find little advertising
interest). The conservatism of tradition seems to go
hand-in-hand with the conservatism of industry interests and
investments.